1. Field of the Invention
The present invention relates, in general, to a ballast for a circuit for lighting discharge lamps, and, more particularly, toga ballast for multiple lamps, which is used in a circuit for simultaneously lighting multiple discharge lamps, and a method of manufacturing the ballast.
2. Description of the Related Art
Once a discharge lamp, which is a lamp that generates light by means of an internal electrical discharge between electrodes in a gas, is directly connected to a power supply and current starts to flow through the discharge lamp, the current suddenly increases, thus instantaneously breaking down the electrode terminal or seal of the discharge lamp. Therefore, a ballast is installed between the power supply and the discharge lamp to suitably control the current in the discharge lamp.
Generally, a magnetic ballast is composed of one or more coils, each having a core, which has inductance, and is configured to supply a constant current by preventing the current from increasing.
A conventional ballast is formed such that an I-type core and an E-type core, each composed of a plurality of silicon steel sheets according to the relevant capacity, are mutually assembled to a bobbin around which coils are wound so as to form magnetic force lines in a predetermined movement direction.
However, such a conventional ballast is configured to light only one discharge lamp, so it is problematic in that it cannot be used in a circuit for simultaneously lighting multiple discharge lamps. Further, the conventional ballast is problematic because welding must be performed when the bobbin, the I-type core, and the E-type core are mutually assembled, so light and gas generated during welding not only cause air pollution but are also harmful to humans, thus deteriorating production efficiency and increasing manufacturing costs.